How to create a curved road in blender
You could do it this way:

Create your road section, subdivide it a bit:



Create your road profile with a curve.
In Edit mode, enable the normals display and make sure that the direction is correct, otherwise press W &gt; Switch Direction:



Select your road section and put it at the same point as the curve origin (select the curve, then ShiftS &gt; Cursor to Selected, then select the mesh and ShiftS &gt; Selection to Cursor):



Give your road section an Array modifier, choose the amount of iterations (Count value), enable the Merge option.
Give your road section an Curve modifier, choose the curve as Object. The object will follow along the curve. You can add a Subdivision Surface and click Smooth Shading to smooth it.


Now let's imagine that you want a bumpy terrain:

Create your terrain, create your curve, subdivide your curve a bit:



Give your curve a Shrinkwrap modifier so that it follows the terrain relief. Apply the modifier:



Follow the same steps as before, create a road section and make it follow the curve:



Once you are about glad, apply the Array and the Curve modifiers and bring some corrections manually to make a correct topology and to make it stick nicely to the terrain:



Last possibility: You need the road to be flat on a bumpy terrain. In that case you can use a Shrinkwrap modifier on the terrain so that it sticks to the road, then smooth its topology in Sculpt mode, see here.